The optical pickup is applied in compact disk, laser disk, video disk, photo-electro magnetic disk and the like, is made to scan information recorded on a disk by irradiating a semi-conductor laser in controlling to several μm diameter spot by lens, and consists of, commonly, an optical flame which fixes optical element and the like of photo-emitting element, photo-detection element mirror and the like, and of an actuator part which makes an object lens and an object lens holder to make follow-up to the movement of the optical lens, and of a base flame which forms an optical path of the optical flame by keeping the actuator part.
In recent years, the weight reduction and cost reduction of the optical pick up are accelerated, and a trial to replace the component material from a metal to a resin has been done, and especially, a liquid crystal polyester resin among thermoplastic resins has been paid attention as the optical pickup component such as the lens holder and the base flame for the excellence of mechanical properties, processability, dimensional accuracy, heat resistance, and vibration damping properties (Refer to Patent Document 1).
However, information which is dealt by the recent digital disc driving device, is made to have a large capacity, and a scanning is made to speed-up, and also, the occupied volume of the optical pickup component itself is made to be required to reduce so that more sophisticated characteristic properties have been made to be required even to the made-up liquid crystal polyester resin. For example, a composition with specific liquid crystal polyester and inorganic filler which corresponds to the optical pickup having the complicate structure and the thin thickness part (Refer to Patent Document 2), a composition containing cycloolefin polymer having small variation of dimensional accuracy with time (Refer to Patent Document 3), a composition containing specific particulate filler material corresponding to vibration damping properties and low flash properties (Refer to Patent Document 4), a composition containing the specific liquid crystal polyester and glass fiber (Refer to Patent Document 5), have been proposed.
Patent Document 1: JP62-236143 A
Patent Document 2: JP08-220407 A
Patent Document 3: JP11-185272 A
Patent Document 4: JP2000-273292 A
Patent Document 5: JP2001-288342 A
However, the above proposals do not realize or anticipate sufficiently to the items which are required for the recent optical pickup lens holder.
Initially, the optical pickup component, of which structure is made to be circular, ellipse or polygonal sheet form structure, as the essential requirement of space saving and energy saving of the device, is required to high flowability and good appearance having no occurrence of flash while the injection molding, and simultaneously, the component material is required to aim at the lower specific gravity for the purpose of improving the driving sensitivity and of saving the electric power consumption while driving the pickup.
Moreover, the start of the use of non-lead soldering has been studied from the environmental problem so that the soldering heat resistance becomes important element more than ever before. In the sheet form lens holder having thin thickness part the problem has been made to be especially important.
Furthermore, the influence by heat emitted from the driving coil while driving has become in the news as the problem accompanying with the downsizing of the device. Namely, generally for the optical pickup lens, the plastic lens is applied from the point of the cost and the driving coil is made to provide in adjacent position of the lens because of the downsizing, and when the atmospheric temperature in the vicinity of the optical pickup lens raises by heat emitted from the driving coil while driving, thermal expansion of the lens occurs so that phenomena which a spot of a laser deviates from the point occurs and it is found to cause scanning error.
Especially, incase that the optical pickup lens holder has a structure in which the focusing coil attached to the same lens holder locates in the adjacent position to the lens attached to the same lens holder, for example, in case that the optical lens holder has an opening port in the center, and the coil is inserted into said opening port, the problem has become important. Such structures are disclosed in, for example, JP7-29194A, JP10-21570A.